import sys
from time import sleep
import pygame
from bullet import Bullet
from alien import Alien

def check_keydown_events(event,ai_settings,screen,ship,bullets):
    # 响应按键
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings,screen,ship,bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def fire_bullet(ai_settings,screen,ship,bullets):
    # 创建一颗子弹，并将其加入编组bullets中
    if len(bullets) < ai_settings.bullet_allowed:
        new_bullet = Bullet(ai_settings,screen,ship)
        bullets.add(new_bullet)
            
def check_up_events(event,ship):
    # 响应松开
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left = False

def check_events(ai_settings,screen,stats,scoreboard,play_button,ship,aliens,bullets):
    '''响应按键和鼠标事件'''
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets)

        elif event.type == pygame.KEYUP:
            check_up_events(event,ship)

        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x,mouse_y = pygame.mouse.get_pos()
            
            check_play_button(ai_settings,screen,stats,scoreboard,play_button,ship,aliens,bullets,mouse_x,mouse_y)

def check_play_button(ai_settings,screen,stats,scoreboard,play_button,ship,aliens,bullets,mouse_x,mouse_y):
    # 在玩家单击Play按钮时开始游戏
    button_clcked = play_button.rect.collidepoint(mouse_x,mouse_y)

    if button_clcked and not stats.game_active:
        # 重置游戏设置
        ai_settings.initialize_dynamic_settings()

        # 隐藏光标
        pygame.mouse.set_visible(False)

        #重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True

        # 重置记分牌图像
        scoreboard.prep_score()
        scoreboard.prep_high_score()
        scoreboard.prep_level()
        scoreboard.prep_ships()

        #清空外星人和子弹列表
        aliens.empty()
        bullets.empty()

        # 创建一群新的外星人，并将飞船居中
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()


def update_screen(ai_settings,screen,stats,scoreboard,ship,aliens,bullets,play_button):
    # 更新屏幕上的图像，并切换到新屏幕

    #每次循环时都重绘屏幕
    screen.fill(ai_settings.bg_color)

    # 在飞船和外星人后边绘制所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()

    ship.blitme()
    aliens.draw(screen)

    # 显示得分
    scoreboard.show_score()

    # 如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()

    # 让最近绘制的屏幕可见
    pygame.display.flip()


def update_bullets(ai_settings,screen,stats,scoreboard,ship,aliens,bullets):

    # 更新子弹位置
    bullets.update()
    # 删除已消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
    check_bullet_alien_collisions(ai_settings,screen,stats,scoreboard,ship,aliens,bullets)

def check_bullet_alien_collisions(ai_settings,screen,stats,scoreboard,ship,aliens,bullets):
    # 检查是否有子弹击中外星人，击中则删除相应的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)
    if collisions:
        for aliens in collisions.values():
            stats.score += ai_settings.alien_points * len(aliens)
            scoreboard.prep_score()
        check_high_score(stats, scoreboard)

    if len(aliens) == 0:
        #删除现有的子弹，并新建一群外星人
        bullets.empty()
        
        ai_settings.increase_speed() #增加游戏难度

        # 提高等级
        stats.level += 1
        scoreboard.prep_level()


        create_fleet(ai_settings,screen,ship,aliens)


def get_number_aliens_x(ai_settings,alien_width):
    # 计算每行可以容纳多少个外星人

    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    return number_aliens_x


def get_number_rows(ai_settings,ship_height,alien_height):
    # 计算屏幕可以容纳多少行外星人
    available_space_y = (ai_settings.screen_height - (3 * alien_height) - ship_height )
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows


def create_alien(ai_settings,screen,aliens,alien_number,row_number):
    # 创建一个外星人并将其加入当前行

    alien = Alien(ai_settings,screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)
  
def create_fleet(ai_settings,screen,ship,aliens):
    # 创建外星人群

    # 创建一个外星人并计算一行可以容纳多少个外星人
    
    alien = Alien(ai_settings,screen)
    number_aliens_x = get_number_aliens_x(ai_settings,alien.rect.width)
    number_rows = get_number_rows(ai_settings,ship.rect.height,alien.rect.height)

    
    # 创建第一行外星人
    for row_number in range(number_rows):
        for alien_number in range(number_aliens_x):
            create_alien(ai_settings,screen,aliens,alien_number,row_number)


def check_fleet_edges(ai_settings,aliens):
    #有外星人到达边缘时采取的措施
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings,aliens)
            break


def change_fleet_direction(ai_settings,aliens):
    #将整群外星人下移，并改变它们的方向
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def ship_hit(ai_settings, screen, stats, scoreboard, ship, aliens, bullets):
    # 响应被外星人撞到的飞船
    if stats.ships_left > 0 :

        # 将ships_left 减1
        stats.ships_left -= 1

        # 更新记分牌
        scoreboard.prep_ships()

        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        # 创建一群新的外星人，并将飞船放到屏幕底端中央
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()

        #暂停
        sleep(0.5)
    else :
        stats.game_active = False
        # 显示光标
        pygame.mouse.set_visible(True)
        

def check_aliens_bottom(ai_settings, screen, stats, scoreboard, ship, aliens, bullets):
    # 检查是否有外星人到达屏幕底端
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            # 像碰到飞船一样处理
            ship_hit(ai_settings, screen, stats, scoreboard, ship, aliens, bullets)
            break


def update_aliens(ai_settings,screen,stats,scoreboard,ship,aliens,bullets):
    # 更新外星人群中所有外星人的位置
    check_fleet_edges(ai_settings,aliens)
    aliens.update()

    #检测外星人与飞船的碰撞
    if pygame.sprite.spritecollideany(ship,aliens):
        ship_hit(ai_settings, screen, stats, scoreboard, ship, aliens, bullets)

    # 检查是否有外星人到达屏幕底端
    check_aliens_bottom(ai_settings, screen, stats, scoreboard, ship, aliens, bullets)
    
def check_high_score(stats, scoreboard): 
    """检查是否诞生了新的最高得分""" 
    if stats.score > stats.high_score: 
        stats.high_score = stats.score 
        scoreboard.prep_high_score()














